module TcPatSyn ( tcPatSynDecl, tcPatSynBuilderBind
, tcPatSynBuilderOcc, nonBidirectionalErr
) where
import GhcPrelude
import HsSyn
import TcPat
import Type( mkEmptyTCvSubst, tidyTyVarBinders, tidyTypes, tidyType )
import TcRnMonad
import TcSigs( emptyPragEnv, completeSigFromId )
import TcType( mkMinimalBySCs )
import TcEnv
import TcMType
import TcHsSyn( zonkTyVarBindersX, zonkTcTypeToTypes
, zonkTcTypeToType, emptyZonkEnv )
import TysPrim
import TysWiredIn ( runtimeRepTy )
import Name
import SrcLoc
import PatSyn
import NameSet
import Panic
import Outputable
import FastString
import Var
import VarEnv( emptyTidyEnv, mkInScopeSet )
import Id
import IdInfo( RecSelParent(..), setLevityInfoWithType )
import TcBinds
import BasicTypes
import TcSimplify
import TcUnify
import TcType
import TcEvidence
import BuildTyCl
import VarSet
import MkId
import TcTyDecls
import ConLike
import FieldLabel
import Bag
import Util
import ErrUtils
import Control.Monad ( zipWithM )
import Data.List( partition )
#include "HsVersions.h"
tcPatSynDecl :: PatSynBind GhcRn GhcRn
-> Maybe TcSigInfo
-> TcM (LHsBinds GhcTc, TcGblEnv)
tcPatSynDecl psb mb_sig
= recoverM (recoverPSB psb) $
case mb_sig of
Nothing -> tcInferPatSynDecl psb
Just (TcPatSynSig tpsi) -> tcCheckPatSynDecl psb tpsi
_ -> panic "tcPatSynDecl"
recoverPSB :: PatSynBind GhcRn GhcRn
-> TcM (LHsBinds GhcTc, TcGblEnv)
recoverPSB (PSB { psb_id = L _ name, psb_args = details })
= do { matcher_name <- newImplicitBinder name mkMatcherOcc
; let placeholder = AConLike $ PatSynCon $
mk_placeholder matcher_name
; gbl_env <- tcExtendGlobalEnv [placeholder] getGblEnv
; return (emptyBag, gbl_env) }
where
(_arg_names, _rec_fields, is_infix) = collectPatSynArgInfo details
mk_placeholder matcher_name
= mkPatSyn name is_infix
([mkTyVarBinder Specified alphaTyVar], []) ([], [])
[]
alphaTy
(matcher_id, True) Nothing
[]
where
matcher_id = mkLocalId matcher_name $
mkSpecForAllTys [alphaTyVar] alphaTy
recoverPSB (XPatSynBind {}) = panic "recoverPSB"
tcInferPatSynDecl :: PatSynBind GhcRn GhcRn
-> TcM (LHsBinds GhcTc, TcGblEnv)
tcInferPatSynDecl (PSB { psb_id = lname@(L _ name), psb_args = details
, psb_def = lpat, psb_dir = dir })
= addPatSynCtxt lname $
do { traceTc "tcInferPatSynDecl {" $ ppr name
; let (arg_names, rec_fields, is_infix) = collectPatSynArgInfo details
; (tclvl, wanted, ((lpat', args), pat_ty))
<- pushLevelAndCaptureConstraints $
tcInferNoInst $ \ exp_ty ->
tcPat PatSyn lpat exp_ty $
mapM tcLookupId arg_names
; let named_taus = (name, pat_ty) : map (\arg -> (getName arg, varType arg)) args
; (qtvs, req_dicts, ev_binds, residual, _)
<- simplifyInfer tclvl NoRestrictions [] named_taus wanted
; top_ev_binds <- checkNoErrs (simplifyTop residual)
; addTopEvBinds top_ev_binds $
do { let (ex_tvs, prov_dicts) = tcCollectEx lpat'
ex_tv_set = mkVarSet ex_tvs
univ_tvs = filterOut (`elemVarSet` ex_tv_set) qtvs
req_theta = map evVarPred req_dicts
; prov_dicts <- mapM zonkId prov_dicts
; let filtered_prov_dicts = mkMinimalBySCs evVarPred prov_dicts
prov_theta = map evVarPred filtered_prov_dicts
; let bad_tvs = [ tv | tv <- univ_tvs
, tyCoVarsOfType (tyVarKind tv)
`intersectsVarSet` ex_tv_set ]
; mapM_ (badUnivTvErr ex_tvs) bad_tvs
; args <- mapM zonkId args
; let bad_args = [ (arg, bad_cos) | arg <- args ++ prov_dicts
, let bad_cos = filterDVarSet isId $
(tyCoVarsOfTypeDSet (idType arg))
, not (isEmptyDVarSet bad_cos) ]
; mapM_ dependentArgErr bad_args
; traceTc "tcInferPatSynDecl }" $ (ppr name $$ ppr ex_tvs)
; tc_patsyn_finish lname dir is_infix lpat'
(mkTyVarBinders Inferred univ_tvs
, req_theta, ev_binds, req_dicts)
(mkTyVarBinders Inferred ex_tvs
, mkTyVarTys ex_tvs, prov_theta
, map (EvExpr . evId) filtered_prov_dicts)
(map nlHsVar args, map idType args)
pat_ty rec_fields } }
tcInferPatSynDecl (XPatSynBind _) = panic "tcInferPatSynDecl"
badUnivTvErr :: [TyVar] -> TyVar -> TcM ()
badUnivTvErr ex_tvs bad_tv
= addErrTc $
vcat [ text "Universal type variable" <+> quotes (ppr bad_tv)
<+> text "has existentially bound kind:"
, nest 2 (ppr_with_kind bad_tv)
, hang (text "Existentially-bound variables:")
2 (vcat (map ppr_with_kind ex_tvs))
, text "Probable fix: give the pattern synoym a type signature"
]
where
ppr_with_kind tv = ppr tv <+> dcolon <+> ppr (tyVarKind tv)
dependentArgErr :: (Id, DTyCoVarSet) -> TcM ()
dependentArgErr (arg, bad_cos)
= addErrTc $
vcat [ text "Iceland Jack! Iceland Jack! Stop torturing me!"
, hang (text "Pattern-bound variable")
2 (ppr arg <+> dcolon <+> ppr (idType arg))
, nest 2 $
hang (text "has a type that mentions pattern-bound coercion"
<> plural bad_co_list <> colon)
2 (pprWithCommas ppr bad_co_list)
, text "Hint: use -fprint-explicit-coercions to see the coercions"
, text "Probable fix: add a pattern signature" ]
where
bad_co_list = dVarSetElems bad_cos
tcCheckPatSynDecl :: PatSynBind GhcRn GhcRn
-> TcPatSynInfo
-> TcM (LHsBinds GhcTc, TcGblEnv)
tcCheckPatSynDecl psb@PSB{ psb_id = lname@(L _ name), psb_args = details
, psb_def = lpat, psb_dir = dir }
TPSI{ patsig_implicit_bndrs = implicit_tvs
, patsig_univ_bndrs = explicit_univ_tvs, patsig_prov = prov_theta
, patsig_ex_bndrs = explicit_ex_tvs, patsig_req = req_theta
, patsig_body_ty = sig_body_ty }
= addPatSynCtxt lname $
do { let decl_arity = length arg_names
(arg_names, rec_fields, is_infix) = collectPatSynArgInfo details
; traceTc "tcCheckPatSynDecl" $
vcat [ ppr implicit_tvs, ppr explicit_univ_tvs, ppr req_theta
, ppr explicit_ex_tvs, ppr prov_theta, ppr sig_body_ty ]
; (arg_tys, pat_ty) <- case tcSplitFunTysN decl_arity sig_body_ty of
Right stuff -> return stuff
Left missing -> wrongNumberOfParmsErr name decl_arity missing
; let bad_tvs = filter (`elemVarSet` tyCoVarsOfType pat_ty) explicit_ex_tvs
; checkTc (null bad_tvs) $
hang (sep [ text "The result type of the signature for" <+> quotes (ppr name) <> comma
, text "namely" <+> quotes (ppr pat_ty) ])
2 (text "mentions existential type variable" <> plural bad_tvs
<+> pprQuotedList bad_tvs)
; let univ_fvs = closeOverKinds $
(tyCoVarsOfTypes (pat_ty : req_theta) `extendVarSetList` explicit_univ_tvs)
(extra_univ, extra_ex) = partition ((`elemVarSet` univ_fvs) . binderVar) implicit_tvs
univ_bndrs = extra_univ ++ mkTyVarBinders Specified explicit_univ_tvs
ex_bndrs = extra_ex ++ mkTyVarBinders Specified explicit_ex_tvs
univ_tvs = binderVars univ_bndrs
ex_tvs = binderVars ex_bndrs
; req_dicts <- newEvVars req_theta
; (tclvl, wanted, (lpat', (ex_tvs', prov_dicts, args'))) <-
ASSERT2( equalLength arg_names arg_tys, ppr name $$ ppr arg_names $$ ppr arg_tys )
pushLevelAndCaptureConstraints $
tcExtendTyVarEnv univ_tvs $
tcExtendKindEnvList [(getName (binderVar ex_tv), APromotionErr PatSynExPE)
| ex_tv <- extra_ex] $
tcPat PatSyn lpat (mkCheckExpType pat_ty) $
do { let in_scope = mkInScopeSet (mkVarSet univ_tvs)
empty_subst = mkEmptyTCvSubst in_scope
; (subst, ex_tvs') <- mapAccumLM newMetaTyVarX empty_subst ex_tvs
; traceTc "tcpatsyn1" (vcat [ ppr v <+> dcolon <+> ppr (tyVarKind v) | v <- ex_tvs])
; traceTc "tcpatsyn2" (vcat [ ppr v <+> dcolon <+> ppr (tyVarKind v) | v <- ex_tvs'])
; let prov_theta' = substTheta subst prov_theta
; prov_dicts <- mapM (emitWanted (ProvCtxtOrigin psb)) prov_theta'
; args' <- zipWithM (tc_arg subst) arg_names arg_tys
; return (ex_tvs', prov_dicts, args') }
; let skol_info = SigSkol (PatSynCtxt name) pat_ty []
; (implics, ev_binds) <- buildImplicationFor tclvl skol_info univ_tvs req_dicts wanted
; simplifyTopImplic implics
; traceTc "tcCheckPatSynDecl }" $ ppr name
; tc_patsyn_finish lname dir is_infix lpat'
(univ_bndrs, req_theta, ev_binds, req_dicts)
(ex_bndrs, mkTyVarTys ex_tvs', prov_theta, prov_dicts)
(args', arg_tys)
pat_ty rec_fields }
where
tc_arg :: TCvSubst -> Name -> Type -> TcM (LHsExpr GhcTcId)
tc_arg subst arg_name arg_ty
= do {
arg_id <- tcLookupId arg_name
; wrap <- tcSubType_NC GenSigCtxt
(idType arg_id)
(substTyUnchecked subst arg_ty)
; return (mkLHsWrap wrap $ nlHsVar arg_id) }
tcCheckPatSynDecl (XPatSynBind _) _ = panic "tcCheckPatSynDecl"
collectPatSynArgInfo :: HsPatSynDetails (Located Name)
-> ([Name], [Name], Bool)
collectPatSynArgInfo details =
case details of
PrefixCon names -> (map unLoc names, [], False)
InfixCon name1 name2 -> (map unLoc [name1, name2], [], True)
RecCon names -> (vars, sels, False)
where
(vars, sels) = unzip (map splitRecordPatSyn names)
where
splitRecordPatSyn :: RecordPatSynField (Located Name)
-> (Name, Name)
splitRecordPatSyn (RecordPatSynField { recordPatSynPatVar = L _ patVar
, recordPatSynSelectorId = L _ selId })
= (patVar, selId)
addPatSynCtxt :: Located Name -> TcM a -> TcM a
addPatSynCtxt (L loc name) thing_inside
= setSrcSpan loc $
addErrCtxt (text "In the declaration for pattern synonym"
<+> quotes (ppr name)) $
thing_inside
wrongNumberOfParmsErr :: Name -> Arity -> Arity -> TcM a
wrongNumberOfParmsErr name decl_arity missing
= failWithTc $
hang (text "Pattern synonym" <+> quotes (ppr name) <+> ptext (sLit "has")
<+> speakNOf decl_arity (text "argument"))
2 (text "but its type signature has" <+> int missing <+> text "fewer arrows")
tc_patsyn_finish :: Located Name
-> HsPatSynDir GhcRn
-> Bool
-> LPat GhcTc
-> ([TcTyVarBinder], [PredType], TcEvBinds, [EvVar])
-> ([TcTyVarBinder], [TcType], [PredType], [EvTerm])
-> ([LHsExpr GhcTcId], [TcType])
-> TcType
-> [Name]
-> TcM (LHsBinds GhcTc, TcGblEnv)
tc_patsyn_finish lname dir is_infix lpat'
(univ_tvs, req_theta, req_ev_binds, req_dicts)
(ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys)
pat_ty field_labels
= do {
(ze, univ_tvs') <- zonkTyVarBindersX emptyZonkEnv univ_tvs
; req_theta' <- zonkTcTypeToTypes ze req_theta
; (ze, ex_tvs') <- zonkTyVarBindersX ze ex_tvs
; prov_theta' <- zonkTcTypeToTypes ze prov_theta
; pat_ty' <- zonkTcTypeToType ze pat_ty
; arg_tys' <- zonkTcTypeToTypes ze arg_tys
; let (env1, univ_tvs) = tidyTyVarBinders emptyTidyEnv univ_tvs'
(env2, ex_tvs) = tidyTyVarBinders env1 ex_tvs'
req_theta = tidyTypes env2 req_theta'
prov_theta = tidyTypes env2 prov_theta'
arg_tys = tidyTypes env2 arg_tys'
pat_ty = tidyType env2 pat_ty'
; traceTc "tc_patsyn_finish {" $
ppr (unLoc lname) $$ ppr (unLoc lpat') $$
ppr (univ_tvs, req_theta, req_ev_binds, req_dicts) $$
ppr (ex_tvs, prov_theta, prov_dicts) $$
ppr args $$
ppr arg_tys $$
ppr pat_ty
; (matcher_id, matcher_bind) <- tcPatSynMatcher lname lpat'
(binderVars univ_tvs, req_theta, req_ev_binds, req_dicts)
(binderVars ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys)
pat_ty
; builder_id <- mkPatSynBuilderId dir lname
univ_tvs req_theta
ex_tvs prov_theta
arg_tys pat_ty
; let mkFieldLabel name = FieldLabel { flLabel = occNameFS (nameOccName name)
, flIsOverloaded = False
, flSelector = name }
field_labels' = map mkFieldLabel field_labels
; let patSyn = mkPatSyn (unLoc lname) is_infix
(univ_tvs, req_theta)
(ex_tvs, prov_theta)
arg_tys
pat_ty
matcher_id builder_id
field_labels'
; let rn_rec_sel_binds = mkPatSynRecSelBinds patSyn (patSynFieldLabels patSyn)
tything = AConLike (PatSynCon patSyn)
; tcg_env <- tcExtendGlobalEnv [tything] $
tcRecSelBinds rn_rec_sel_binds
; traceTc "tc_patsyn_finish }" empty
; return (matcher_bind, tcg_env) }
tcPatSynMatcher :: Located Name
-> LPat GhcTc
-> ([TcTyVar], ThetaType, TcEvBinds, [EvVar])
-> ([TcTyVar], [TcType], ThetaType, [EvTerm])
-> ([LHsExpr GhcTcId], [TcType])
-> TcType
-> TcM ((Id, Bool), LHsBinds GhcTc)
tcPatSynMatcher (L loc name) lpat
(univ_tvs, req_theta, req_ev_binds, req_dicts)
(ex_tvs, ex_tys, prov_theta, prov_dicts)
(args, arg_tys) pat_ty
= do { rr_name <- newNameAt (mkTyVarOcc "rep") loc
; tv_name <- newNameAt (mkTyVarOcc "r") loc
; let rr_tv = mkTyVar rr_name runtimeRepTy
rr = mkTyVarTy rr_tv
res_tv = mkTyVar tv_name (tYPE rr)
res_ty = mkTyVarTy res_tv
is_unlifted = null args && null prov_dicts
(cont_args, cont_arg_tys)
| is_unlifted = ([nlHsVar voidPrimId], [voidPrimTy])
| otherwise = (args, arg_tys)
cont_ty = mkInfSigmaTy ex_tvs prov_theta $
mkFunTys cont_arg_tys res_ty
fail_ty = mkFunTy voidPrimTy res_ty
; matcher_name <- newImplicitBinder name mkMatcherOcc
; scrutinee <- newSysLocalId (fsLit "scrut") pat_ty
; cont <- newSysLocalId (fsLit "cont") cont_ty
; fail <- newSysLocalId (fsLit "fail") fail_ty
; let matcher_tau = mkFunTys [pat_ty, cont_ty, fail_ty] res_ty
matcher_sigma = mkInfSigmaTy (rr_tv:res_tv:univ_tvs) req_theta matcher_tau
matcher_id = mkExportedVanillaId matcher_name matcher_sigma
inst_wrap = mkWpEvApps prov_dicts <.> mkWpTyApps ex_tys
cont' = foldl nlHsApp (mkLHsWrap inst_wrap (nlHsVar cont)) cont_args
fail' = nlHsApps fail [nlHsVar voidPrimId]
args = map nlVarPat [scrutinee, cont, fail]
lwpat = noLoc $ WildPat pat_ty
cases = if isIrrefutableHsPat lpat
then [mkHsCaseAlt lpat cont']
else [mkHsCaseAlt lpat cont',
mkHsCaseAlt lwpat fail']
body = mkLHsWrap (mkWpLet req_ev_binds) $
L (getLoc lpat) $
HsCase noExt (nlHsVar scrutinee) $
MG{ mg_alts = L (getLoc lpat) cases
, mg_ext = MatchGroupTc [pat_ty] res_ty
, mg_origin = Generated
}
body' = noLoc $
HsLam noExt $
MG{ mg_alts = noLoc [mkSimpleMatch LambdaExpr
args body]
, mg_ext = MatchGroupTc [pat_ty, cont_ty, fail_ty] res_ty
, mg_origin = Generated
}
match = mkMatch (mkPrefixFunRhs (L loc name)) []
(mkHsLams (rr_tv:res_tv:univ_tvs)
req_dicts body')
(noLoc (EmptyLocalBinds noExt))
mg :: MatchGroup GhcTc (LHsExpr GhcTc)
mg = MG{ mg_alts = L (getLoc match) [match]
, mg_ext = MatchGroupTc [] res_ty
, mg_origin = Generated
}
; let bind = FunBind{ fun_ext = emptyNameSet
, fun_id = L loc matcher_id
, fun_matches = mg
, fun_co_fn = idHsWrapper
, fun_tick = [] }
matcher_bind = unitBag (noLoc bind)
; traceTc "tcPatSynMatcher" (ppr name $$ ppr (idType matcher_id))
; traceTc "tcPatSynMatcher" (ppr matcher_bind)
; return ((matcher_id, is_unlifted), matcher_bind) }
mkPatSynRecSelBinds :: PatSyn
-> [FieldLabel]
-> [(Id, LHsBind GhcRn)]
mkPatSynRecSelBinds ps fields
= [ mkOneRecordSelector [PatSynCon ps] (RecSelPatSyn ps) fld_lbl
| fld_lbl <- fields ]
isUnidirectional :: HsPatSynDir a -> Bool
isUnidirectional Unidirectional = True
isUnidirectional ImplicitBidirectional = False
isUnidirectional ExplicitBidirectional{} = False
mkPatSynBuilderId :: HsPatSynDir a -> Located Name
-> [TyVarBinder] -> ThetaType
-> [TyVarBinder] -> ThetaType
-> [Type] -> Type
-> TcM (Maybe (Id, Bool))
mkPatSynBuilderId dir (L _ name)
univ_bndrs req_theta ex_bndrs prov_theta
arg_tys pat_ty
| isUnidirectional dir
= return Nothing
| otherwise
= do { builder_name <- newImplicitBinder name mkBuilderOcc
; let theta = req_theta ++ prov_theta
need_dummy_arg = isUnliftedType pat_ty && null arg_tys && null theta
builder_sigma = add_void need_dummy_arg $
mkForAllTys univ_bndrs $
mkForAllTys ex_bndrs $
mkFunTys theta $
mkFunTys arg_tys $
pat_ty
builder_id = mkExportedVanillaId builder_name builder_sigma
builder_id' = modifyIdInfo (`setLevityInfoWithType` pat_ty) builder_id
; return (Just (builder_id', need_dummy_arg)) }
where
tcPatSynBuilderBind :: PatSynBind GhcRn GhcRn
-> TcM (LHsBinds GhcTc)
tcPatSynBuilderBind (PSB { psb_id = L loc name, psb_def = lpat
, psb_dir = dir, psb_args = details })
| isUnidirectional dir
= return emptyBag
| Left why <- mb_match_group
= setSrcSpan (getLoc lpat) $ failWithTc $
vcat [ hang (text "Invalid right-hand side of bidirectional pattern synonym"
<+> quotes (ppr name) <> colon)
2 why
, text "RHS pattern:" <+> ppr lpat ]
| Right match_group <- mb_match_group
= do { patsyn <- tcLookupPatSyn name
; case patSynBuilder patsyn of {
Nothing -> return emptyBag ;
Just (builder_id, need_dummy_arg) ->
do {
let match_group' | need_dummy_arg = add_dummy_arg match_group
| otherwise = match_group
bind = FunBind { fun_ext = placeHolderNamesTc
, fun_id = L loc (idName builder_id)
, fun_matches = match_group'
, fun_co_fn = idHsWrapper
, fun_tick = [] }
sig = completeSigFromId (PatSynCtxt name) builder_id
; traceTc "tcPatSynBuilderBind {" $
ppr patsyn $$ ppr builder_id <+> dcolon <+> ppr (idType builder_id)
; (builder_binds, _) <- tcPolyCheck emptyPragEnv sig (noLoc bind)
; traceTc "tcPatSynBuilderBind }" $ ppr builder_binds
; return builder_binds } } }
| otherwise = panic "tcPatSynBuilderBind"
where
mb_match_group
= case dir of
ExplicitBidirectional explicit_mg -> Right explicit_mg
ImplicitBidirectional -> fmap mk_mg (tcPatToExpr name args lpat)
Unidirectional -> panic "tcPatSynBuilderBind"
mk_mg :: LHsExpr GhcRn -> MatchGroup GhcRn (LHsExpr GhcRn)
mk_mg body = mkMatchGroup Generated [builder_match]
where
builder_args = [L loc (VarPat noExt (L loc n)) | L loc n <- args]
builder_match = mkMatch (mkPrefixFunRhs (L loc name))
builder_args body
(noLoc (EmptyLocalBinds noExt))
args = case details of
PrefixCon args -> args
InfixCon arg1 arg2 -> [arg1, arg2]
RecCon args -> map recordPatSynPatVar args
add_dummy_arg :: MatchGroup GhcRn (LHsExpr GhcRn)
-> MatchGroup GhcRn (LHsExpr GhcRn)
add_dummy_arg mg@(MG { mg_alts = L l [L loc match@(Match { m_pats = pats })] })
= mg { mg_alts = L l [L loc (match { m_pats = nlWildPatName : pats })] }
add_dummy_arg other_mg = pprPanic "add_dummy_arg" $
pprMatches other_mg
tcPatSynBuilderBind (XPatSynBind _) = panic "tcPatSynBuilderBind"
tcPatSynBuilderOcc :: PatSyn -> TcM (HsExpr GhcTcId, TcSigmaType)
tcPatSynBuilderOcc ps
| Just (builder_id, add_void_arg) <- builder
, let builder_expr = HsConLikeOut noExt (PatSynCon ps)
builder_ty = idType builder_id
= return $
if add_void_arg
then ( builder_expr
, tcFunResultTy builder_ty )
else (builder_expr, builder_ty)
| otherwise
= nonBidirectionalErr name
where
name = patSynName ps
builder = patSynBuilder ps
add_void :: Bool -> Type -> Type
add_void need_dummy_arg ty
| need_dummy_arg = mkFunTy voidPrimTy ty
| otherwise = ty
tcPatToExpr :: Name -> [Located Name] -> LPat GhcRn
-> Either MsgDoc (LHsExpr GhcRn)
tcPatToExpr name args pat = go pat
where
lhsVars = mkNameSet (map unLoc args)
mkPrefixConExpr :: Located Name -> [LPat GhcRn]
-> Either MsgDoc (HsExpr GhcRn)
mkPrefixConExpr lcon@(L loc _) pats
= do { exprs <- mapM go pats
; return (foldl (\x y -> HsApp noExt (L loc x) y)
(HsVar noExt lcon) exprs) }
mkRecordConExpr :: Located Name -> HsRecFields GhcRn (LPat GhcRn)
-> Either MsgDoc (HsExpr GhcRn)
mkRecordConExpr con fields
= do { exprFields <- mapM go fields
; return (RecordCon noExt con exprFields) }
go :: LPat GhcRn -> Either MsgDoc (LHsExpr GhcRn)
go (L loc p) = L loc <$> go1 p
go1 :: Pat GhcRn -> Either MsgDoc (HsExpr GhcRn)
go1 (ConPatIn con info)
= case info of
PrefixCon ps -> mkPrefixConExpr con ps
InfixCon l r -> mkPrefixConExpr con [l,r]
RecCon fields -> mkRecordConExpr con fields
go1 (SigPat _ pat) = go1 (unLoc pat)
go1 (VarPat _ (L l var))
| var `elemNameSet` lhsVars
= return $ HsVar noExt (L l var)
| otherwise
= Left (quotes (ppr var) <+> text "is not bound by the LHS of the pattern synonym")
go1 (ParPat _ pat) = fmap (HsPar noExt) $ go pat
go1 p@(ListPat reb pats)
| Nothing <- reb = do { exprs <- mapM go pats
; return $ ExplicitList noExt Nothing exprs }
| otherwise = notInvertibleListPat p
go1 (TuplePat _ pats box) = do { exprs <- mapM go pats
; return $ ExplicitTuple noExt
(map (noLoc . (Present noExt)) exprs)
box }
go1 (SumPat _ pat alt arity) = do { expr <- go1 (unLoc pat)
; return $ ExplicitSum noExt alt arity
(noLoc expr)
}
go1 (LitPat _ lit) = return $ HsLit noExt lit
go1 (NPat _ (L _ n) mb_neg _)
| Just neg <- mb_neg = return $ unLoc $ nlHsSyntaxApps neg
[noLoc (HsOverLit noExt n)]
| otherwise = return $ HsOverLit noExt n
go1 (ConPatOut{}) = panic "ConPatOut in output of renamer"
go1 (CoPat{}) = panic "CoPat in output of renamer"
go1 (SplicePat _ (HsSpliced _ _ (HsSplicedPat pat)))
= go1 pat
go1 (SplicePat _ (HsSpliced{})) = panic "Invalid splice variety"
go1 p@(BangPat {}) = notInvertible p
go1 p@(LazyPat {}) = notInvertible p
go1 p@(WildPat {}) = notInvertible p
go1 p@(AsPat {}) = notInvertible p
go1 p@(ViewPat {}) = notInvertible p
go1 p@(NPlusKPat {}) = notInvertible p
go1 p@(XPat {}) = notInvertible p
go1 p@(SplicePat _ (HsTypedSplice {})) = notInvertible p
go1 p@(SplicePat _ (HsUntypedSplice {})) = notInvertible p
go1 p@(SplicePat _ (HsQuasiQuote {})) = notInvertible p
go1 p@(SplicePat _ (XSplice {})) = notInvertible p
notInvertible p = Left (not_invertible_msg p)
not_invertible_msg p
= text "Pattern" <+> quotes (ppr p) <+> text "is not invertible"
$+$ hang (text "Suggestion: instead use an explicitly bidirectional"
<+> text "pattern synonym, e.g.")
2 (hang (text "pattern" <+> pp_name <+> pp_args <+> larrow
<+> ppr pat <+> text "where")
2 (pp_name <+> pp_args <+> equals <+> text "..."))
where
pp_name = ppr name
pp_args = hsep (map ppr args)
notInvertibleListPat p
= Left (vcat [ not_invertible_msg p
, text "Reason: rebindable syntax is on."
, text "This is fixable: add use-case to Trac #14380" ])
nonBidirectionalErr :: Outputable name => name -> TcM a
nonBidirectionalErr name = failWithTc $
text "non-bidirectional pattern synonym"
<+> quotes (ppr name) <+> text "used in an expression"
tcCollectEx
:: LPat GhcTc
-> ( [TyVar]
, [EvVar] )
tcCollectEx pat = go pat
where
go :: LPat GhcTc -> ([TyVar], [EvVar])
go = go1 . unLoc
go1 :: Pat GhcTc -> ([TyVar], [EvVar])
go1 (LazyPat _ p) = go p
go1 (AsPat _ _ p) = go p
go1 (ParPat _ p) = go p
go1 (BangPat _ p) = go p
go1 (ListPat _ ps) = mergeMany . map go $ ps
go1 (TuplePat _ ps _) = mergeMany . map go $ ps
go1 (SumPat _ p _ _) = go p
go1 (ViewPat _ _ p) = go p
go1 con@ConPatOut{} = merge (pat_tvs con, pat_dicts con) $
goConDetails $ pat_args con
go1 (SigPat _ p) = go p
go1 (CoPat _ _ p _) = go1 p
go1 (NPlusKPat _ n k _ geq subtract)
= pprPanic "TODO: NPlusKPat" $ ppr n $$ ppr k $$ ppr geq $$ ppr subtract
go1 _ = empty
goConDetails :: HsConPatDetails GhcTc -> ([TyVar], [EvVar])
goConDetails (PrefixCon ps) = mergeMany . map go $ ps
goConDetails (InfixCon p1 p2) = go p1 `merge` go p2
goConDetails (RecCon HsRecFields{ rec_flds = flds })
= mergeMany . map goRecFd $ flds
goRecFd :: LHsRecField GhcTc (LPat GhcTc) -> ([TyVar], [EvVar])
goRecFd (L _ HsRecField{ hsRecFieldArg = p }) = go p
merge (vs1, evs1) (vs2, evs2) = (vs1 ++ vs2, evs1 ++ evs2)
mergeMany = foldr merge empty
empty = ([], [])